port ST_DumpPoints() to C

[kneufeld]

The current implementation of ST_DumpPoints is in plpgsql - as such it doesn't scale well.

At some point, this function should be ported to C, mimicking ST_Dump.

[bitner]

Hacky test that shows potential performance gain by getting away from the plpgsql looping structure with npoints. Dumping a 2600 point linestring takes almost a second with st_dumppoints and ~30ms with this function.

CREATE OR REPLACE FUNCTION dump_linestring_points(geometry) RETURNS SETOF geometry AS $BODY$ SELECT

(

'SRID=' bar ';POINT(' foo

')' )::geometry

FROM

regexp_split_to_table(

rtrim(

substring(asewkt($1) from 23) ,')'

), ','

) as foo , srid($1) as bar

WHERE st_geometrytype($1)='ST_LineString'; $BODY$ LANGUAGE sql IMMUTABLE STRICT COST 1 ROWS 100;

[strk]

I don't think there's a problem in doing this for 2.0.X, right ?

[robe]

no problem as long as we don't change the front-facing api

[robe]

Nathan said he was interested in doing this. Adding him to cc so he can add his patch to this ticket. pramsey I believe was going to act as mentor

​http://www.postgis.org/pipermail/postgis-devel/2012-September/022009.html

[pramsey]

Committed Nathan Wagner's implementation at r10595